$x: pop;
$y: 123;



div {
  foo: url(bloo/blah.css);
  bar: url(http://foo/bar/hux.css);
  foo: url(fudge#{$x}.css);
  bar: url("http://fudge#{$x}/styles.css");
  hux: url(http://box_#{$y}////fudge#{$x}.css);
  @each $i in (1 2 3 4 5) {
    hux: url(http://box_#{$y}////fudge#{$x}.css);
    foo: url(http://blah.com/bar-#{$i}.css);
  }
  gloo: url("hey#{1+2}.css");
  floo: url(hadoop-#{$y+321}.css);
  flum: image-url("fudge.png", hux);
  /*****/
  $bg: "image.png";
  background: url("#{$bg}");
  //gudge: url(type-of(hello) + length(a b c));
  mudge: url();
  nudge: url();
  pudge: url(http://wiki.jbussdieker.name/skins/common/images/Checker-16x16.png?2012-05-02T13:40:00Z);
}

p:after {
  content:url();
}